The present invention relates to a positive-displacement pump, in particular a vane cell pump, having a pump element, in particular a rotor, which is situated within a contour ring and rotatable between two side surfaces which are provided with a coating. The present invention also relates to a method for manufacturing a coated side surface of a preliminarily described positive-displacement pump.
Positive-displacement pumps, vane cell pumps in particular, of the generic type are known. They have a rotor which rotates between two housing side surfaces or side plates within a contour ring which is also referred to as a stroke ring. The rotor is pivoted and has radial slots into which vanes are displaceably inserted. The rotor, the stroke ring, and the housing side surfaces or side plates delimit between two adjacent vanes a displacer space whose volume changes when the rotor is caused to rotate. This results in a volume increase on the intake side of the vane cell pump which causes an intake of a working medium into the respective displacer space, and a volume decrease on the delivery side which causes conveyance of the working medium out of the respective displacer space. Corresponding to the rotary motion of the rotor, an intake section and a delivery section are formed, the intake section being situated in the area of increasing volumes and the delivery section in the area of decreasing volumes. The intake section is linked to an intake connector of the vane cell pump and the delivery section is linked to a delivery connector. Friction may occur during operation on the contact surfaces between the rotor and the housing side surfaces.
U.S. Pat. No. 6,641,380 discloses a vane pump where a contour or cam ring is between two sides provided by a cover and a pressure plate. U.S. Pat. No. 6,641,380 is hereby incorporated by reference herein. U.S. Pat. No. 6,152,716 discloses a vane pump with a contour ring is provided between two pressure plates forming the sides.